Wyniki wyszukiwania - BazTech

1

On the selection of the coarsest size class in flotation rate characterizations

Orellana Francisca, Rivera Marcelo, Benítez Matías, Belmonte Karyn, Vinnett Luis

Physicochemical Problems of Mineral Processing

|

2023

|

Vol. 59, iss. 5

art. no. 176950

EN

This paper studies size-by-size batch flotation kinetics for the separation of Cu at particle sizes +75 μm, investigating the responses in the -150/+75 μm, -212/+150 μm, -300/+212 μm, -355/+300 μm and +355 μm size fractions. The kinetic results were analyzed to identify classes limited by the maximum achievable recovery or low flotation rates. Combinations of these classes were investigated, emulating the selection of the coarsest size in a kinetic study. The impact of compositing size classes was discussed, emphasizing implications in the identification of difficult-to-float components. The -212/+75 μm classes reached steady recoveries at long flotation times, whereas the -355/+212 μm classes presented sustained increasing recoveries at extended flotation times. Flotation rate distributions in the -212/+75 μm classes exhibited mound-shaped distributions, indicating low fractions of rate constants close to zero (R∞-limited case). Conversely, the -355/+212 μm classes presented reverse J-shaped distributions, with a high fraction of valuable minerals with flotation rates close to zero (rate-limited case). Combining several size classes in the definition of the coarsest size fraction in kinetic characterizations proved to hide the flotation patterns of the less massive constituents (+212 μm classes). The +75 μm and +150 μm cumulative retained classes trended towards steady recoveries, consistently leading to mounded flotation rate distributions. This study highlighted the need for reliable methodologies to select size fractions in kinetic characterizations, as their arbitrary definitions may lead to a misinterpretation of the mineral losses when compositing classes with different flotation responses.

2

Proposition of a bubble-particle attachment model based on DLVO van der Waals and electric double layer interactions for froth flotation modelling

Buchmann Markus, Öktem Gülce, Rudolph Martin, Boogaart K. Gerald van den

Physicochemical Problems of Mineral Processing

|

2022

|

Vol. 58, iss. 5

art. no. 154812

EN

The attachment of bubbles and particles represents one of the sub-processes in froth flotation among others (e.g. collision and detachment). The main interactions present at short distances in such a bubble-particle system are the van der Waals and electrostatic double layer interactions combined in the DLVO theory. In this study, the special features of the attachment process were discussed with a focus on flotation. For the van der Waals interactions, the Hamaker constants were calculated with the help of Lifshitz´ macroscopic theory as a function of the separation distance for specific material combinations. A specific material system (PbS-Water-Air) was used to demonstrate the implementation of bubble-particle attachment of the proposed modelling framework. The effects of additional surfactant/collector and air layers on the solid interface were presented. This framework of layered systems showed that the sign of van der Waals interaction could be turned from repulsive to attractive without the need to extend the DLVO theory. The thickness of the layer as a function of collector adsorption between a particle and a bubble is suggested as a modelling parameter in bubble-particle attachment efficiency.

3

Optimization of flotation efficiency of phosphate minerals in mine tailings using polymeric depressants : experiments and machine learning

Alsafasfeh Ashraf, Alagha Lana, Alzidaneen Ala, Nadendla Venkata Sriram Siddhardh

Physicochemical Problems of Mineral Processing

|

2022

|

Vol. 58, iss. 4

art. no. 150477

EN

In this study, direct froth flotation experiments were conducted on silicate-rich phosphate tailing samples. The average grade of P2O5 in the flotation feed was 21.6% as determined using a combination of spectroscopic techniques including X-ray powder diffraction (XRD), mineral liberation analysis (MLA), and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Two polymers were selected to promote the depression of silicates and enhance the flotation of phosphates: in-house synthesized hybrid polyacrylamide (Hy-PAM) and chitosan. Flotation efficiency of phosphates was evaluated at different flotation conditions including depressant type, depressant dosage, pH, and the flotation time. Results indicated that the optimum flotation efficiency of phosphate minerals (84.6% recovery at 28.6% grade of P2O5) was obtained when Hy-PAM was utilized at the studied range of pH and flotation time. All datasets produced from the flotation experiments were integrated within the framework of machine learning (ML) using artificial neural networks (ANNs). The ANN platform was trained, validated, and successfully employed to predict the process outcomes in relation to the pulp and reagents characteristics, which in turn were used to determine the optimum values of process variables. Coefficient of determination (R2), mean absolute error (MAE), and root-mean-square error (RMSE) were used as model indicators. Optimization results showed that the peak flotation performance could be achieved at higher dosages of both polymers. However, lower pH and shorter flotation time for Hy-PAM, and higher pH and longer flotation time for chitosan, were predicted to give the optimum process efficiency.

4

Effect of the foaming performance of ammonium dibutyl dithiophosphate on the flotation of slime-containing copper sulfide ore

Deng Rongdong, Duan Wenting, Wang Yi, Hu Yuan

Physicochemical Problems of Mineral Processing

|

2022

|

Vol. 58, iss. 6

art. no. 153492

EN

The use of ammonium dibutyl dithiophosphate (ADD) as a collector in the flotation of slimecontaining copper sulfide ore typically produces a sticky froth, which results in poor flotation. The mechanism and effects of copper sulfide ore flotation in synergistic systems comprising ADD and terpenic oil reagents have been systematically investigated to solve this problem. A high ratio of ADD to terpenic oil is not conducive to the flotation of fine-grained copper sulfide ores; however, adjusting this ratio may improve floatation by reducing the effect of the slime. Lowering the ratio from 5:1 to 1:1 increased the copper grade from 17.7% to 20.8%, while the recovery was largely unchanged. Notably, adjusting this ratio also reduced the cost of the flotation reagent. To study the mechanism by which the ADD–to–terpenic oil ratio affects the foam performance, the froth stability tests of the gas–liquid twophase and gas–liquid–solid three-phase systems were performed. Reducing the proportion of ADD reduced the froth water content and weakened the ability of the froth to collect gangue by adsorbtion with copper ions; this reduced gangue entrainment and maximized recovery and product quality.

5

Mechanism of the combined effects of air rate and froth depth on entrainment factor in copper flotation

Wang Lei, Xing Yaowen, Wang Jun

Physicochemical Problems of Mineral Processing

|

2020

|

Vol. 56, iss. 1

43--53

EN

The effect of air rate and froth depth on the entrainment factor in flotation has been extensively studied, but further investigation on the underlying mechanism for their effect is still required. In this study, flotation tests were performed at different air rates and froth depths in a 3 dm3 continuously operated cell using an artificial copper ore. The results showed that entrainment factor was affected by both air rate and froth depth, and the combined effect of these variables on entrainment factor depended strongly on the particle size. The entrainment factor increased with either increasing air rate at a relatively shallow froth or decreasing froth depth at a relatively high air rate. At a very low air rate and deep froth, higher entrainment factor was observed for mid-size and coarse particles. When the entrainment factor was correlated to the effective liquid velocity at the pulp/froth interface, the results indicated that multiple mechanisms were responsible for the effect on entrainment factor. At a relatively high air rate and shallow froth depth, entrainment factor had a linear relationship with the interface effective liquid velocity, suggesting that drag force dominated the change in the entrainment factor when air rate and froth depth were varied. At a very low air rate and deep froth, the entrainment factor for fine particles was found to correlate strongly with the interface effective liquid velocity, while the entrapment of solid particles may be the main reason for the high entrainment factor for mid-size and coarse particles under this condition.

6

Acidified water glass in the selective flotation of scheelite from calcite, Part I: performance and impact of the acid type

Kupka Nathalie, Möckel Robert, Rudolph Martin

Physicochemical Problems of Mineral Processing

|

2020

|

Vol. 56, iss. 2

238--251

EN

To improve the performance of sodium silicate in scheelite flotation and allow the selective separation of scheelite from other semi-soluble salt-type minerals such as calcite, three acids, sulfuric, oxalic and for the first time hydrochloric are used to acidify sodium silicate (also called water glass). A literature review of previous usage of acidified water glass shows that no comparison between acids was made before, that comparisons with alkaline water glass were limited and that the idea that acidified water glass is more efficient at lower dosages has not been proven in scheelite flotation. As a consequence, the impact of the acid type, the ratio between acid and sodium silicate and acid dosage is tested in single mineral flotation and batch flotation experiments. All three acids allow a higher performance of acidified water glass compared to alkaline water glass at lower dosages and with little addition of acid: the tungsten recovery and grade are improved while silicates and to a lesser extent calcium-bearing minerals float less. The dosage of acid is less determining than the mass ratio of the acid to sodium silicate, except in the case of hydrochloric acid. Overall, the acid type does not matter as all three acids perform well in flotation, whereby oxalic and hydrochloric acid are better.

7

Acidified water glass in the selective flotation of scheelite from calcite, part II: species in solution and related mechanism of the depressant

Kupka Nathalie, Kaden Peter, Jantschke Anne, Schach Edgar, Rudolph Martin

Physicochemical Problems of Mineral Processing

|

2020

|

Vol. 56, iss. 5

797--817

EN

Sodium silicate is one of the main depressants against calcite and fluorite in the scheelite flotation industry. In the first part of this article, the authors acidified sodium silicate (AWG) with three acids (sulfuric, oxalic and hydrochloric) to improve its performance. Results showed that acidified water glass outperforms alkaline water glass in terms of selectivity: it increases mainly the grade by further depressing silicates and calcium-bearing minerals. In most cases, AWG requires lower dosages to do so. The effect of acidified water glass is evaluated through Mineral Liberation Analysis (MLA), froth analysis, Raman and Nuclear Magnetic Resonance (NMR) spectroscopy in order to hypothesize its mechanism. MLA shows that AWG affects silicates and sulfides more intensely than semi-soluble salttype minerals. Froth observations indicate other species in solution associated to the acid having an impact on the flotation results. Raman spectroscopy and NMR measurements indicate that the solution undergoes deep depolymerization when water glass is acidified. Lower molecular weight silica species, specifically Si-O monomers such as SiO(OH)3- will be responsible for the depression of the gangue minerals and are the drivers of the selectivity of AWG, more than orthosilicic acid. Depolymerization is more or less effective depending on the mass ratio of the acid to water glass and depending on the acid.

8

Flotation separation of enargite from complex copper concentrates by selective surface oxidation

Li Tangfei, Zhang Yansheng, Zhang Bo, Jiao Fen, Qin Wenqing

Physicochemical Problems of Mineral Processing

|

2019

|

Vol. 55, iss. 4

852--864

EN

In previous study, the promising results of separating enargite from non-arsenic copper sulfides were obtained using selective surface oxidation in pure mineral systems. However, this technology was not well understood in real ores or concentrates. In this study, the flotation separation of enargite from complex copper concentrates by selective surface oxidation was investigated. The effects of regrinding, pulp pH, NaClO concentration, conditioning time and flotation time on separation of enargite from NECu minerals were studied. The mineralogical characteristics of the flotation feed and products were showed as an instructive tool to understand the separation results. According to the results of EDTA extraction, the possible mechanism for separation of enargite from NECu minerals is that enargite is more resistant to oxidized compared to NECu minerals. The following order for the oxidation of NECu minerals and enargite is obtained: chalcopyrite (chalcocite, digenite)> enargite (covellite).

9

A review of the beneficiation of copper-cobalt-bearing minerals in the Democratic Republic of Congo

Shengo Michel Lutandula, Kime Meschac-Bill, Mambwe Matanda Pascal, Nyembo Trésor Kilwa

Journal of Sustainable Mining

|

2019

|

Vol. 18, iss. 4

226--246

EN

Copper and cobalt (Cu-Co) are strategic metals for the Democratic Republic of Congo (DRC), and nearly 20% of the country's GDP is supported by their exports. At present, the country classifies itself as the leading copper producer in Africa with an output in the region of a million tonnes and possesses nearly 60% of the world's reserves of Co; a metal exclusively exported in the form of salts or semi-finished products. Concentrators play a very important role in the growth of Cu-Co metal production, which is needed in order to meet rapidly growing global demand and to increase government revenues through mining royalties. This article reviews the major process flow sheets and reagent suites in practice at concentrators operated in the DRC for the beneficiation of Cu-Co values from various ore types. The comprehensive compilation of pertinent laboratory and industrial data is intended to provide practising specialists, metallurgists, and academics conducting research on Congolese Cu-Co ores with a single well-detailed reference source. Emphasis is placed on froth flotation as the major technique for the beneficiation of Cu-Co minerals.

10

The Effect of Sodium Hexametaphosphate on Natural Flotation Kinetics of Talc Ore

Brezani I., Sisol M., Marcin M.

Inżynieria Mineralna

|

2018

|

R. 19, nr 1

125--130

EN

Ground high-grade ore with the d80 of 150 μm was subjected to a series of batch laboratory flotation tests, aimed at determining the natural flotation kinetics of talc mineral, using Methyl isobutyl carbinol (MIBC) frother as the only reagent. Classical first-order flotation model was used and the flotation kinetics are interpreted using the ultimate recovery (R∞) and flotation rate constant (k). Results are then compared with the kinetics of flotation in the presence of different dosages of the frother, Sodium hexametaphosphate (SHMP) and a mixture of SHMP and Soluble starch (SS) in various ratios. The design of experiment (DoE), evaluated using the Analysis of variance (ANOVA) test for multiple factors was used to calculate the statistical significance of the individual factors on the outcomes of the flotation tests – yield of the froth product, talc concentrate grade, talc recovery and flotation kinetics of both talc and gangue minerals. The effect of SHMP on the flotation kinetics of talc and gangue minerals in terms of affecting the R∞ and k parameters is here discussed in greater detail. Although both SHMP and SHMP/SS mixture was found to improve the overall grade of the talc concentrate, this was achieved at the expense of significantly lower recoveries of the valuable mineral.

PL

Zmielona wysokowartościowa ruda o ziarnie podziałowym d80 = 150 μm została poddana serii laboratoryjnych prób flotacji, mających na celu określenie kinetyki flotacji naturalnej minerałów talku, w obec-ności jedynego środka zbierającego metylo-izobutylokarbinol (MIBC). Zastosowano klasyczny model flotacji pierwszego rzędu gdzie kinetykę flotacji interpretuje się za pomocą współczynnika uzysku R∞ i stałej szybkości flotacji (k). Wyniki porównano z kinetyką flotacji w obecności różnych dawek spieniacza, heksametafosforanu sodu (SHMP) i mieszaniny SHMP i rozpuszczalnej skrobi (SS) w różnych proporcjach. Plan eksperymentu (DoE), oceniono za pomocą analizy wariancji (ANOVA) dla wielu czynników użyto do obliczenia istotności statystycznej parametrów flotacji - wydajność produktu pianowego, zawartość talku, uzysk talku i kinetyka flotacji zarówno minerałów talku, jak i skały płonnej. Wpływ SHMP na kinetykę flotacji minerałów talku i skały płonnej na parametr R∞ i k są omówione bardziej szczegółowo. Chociaż stwierdzono, że dla obu mieszanek SHMP i SHMP / SS poprawie uległ stopień koncentracji talku odbyło się to jednak kosztem znacząco niższych wartości uzysku cennego minerału.

11

Role of calcium and magnesium cations in the interactions between kaolinite and chalcopyrite in seawater

Uribe L., Gutierrez L., Laskowski J. S., Castro S.

Physicochemical Problems of Mineral Processing

|

2017

|

Vol. 53, iss. 2

737--749

EN

A number of flotation plants around the world have increased the use of seawater due to limited sources of fresh water. The aim of this research work is to study the role that Mg2+ and Ca2+ ions play in the interactions between kaolinite and chalcopyrite in seawater. In order to achieve this objective, the effect of kaolinite on flotation of chalcopyrite is studied over the pH range from 8 to 11, when flotation is carried out in seawater and in a 0.01M NaCl solution. The influence of calcium, magnesium, sodium, and potassium ions on the extent of depression by kaolinite is evaluated. The micro-flotation results indicate that chalcopyrite is depressed by kaolinite in both 0.01 NaCl solution and seawater. In the 0.01 NaCl solution, the depressing effect of kaolinite decreases as the pH increases from 8 to 11. However, the results obtained using seawater show that the depressing effect of kaolinite is similar to what is observed in a 0.01 NaCl solution only at pH values below 9, but above this pH kaolinite significantly affects the recovery of chalcopyrite. The results from experiments with using solutions containing individual cations show that the depressing action of kaolinite in the presence of Mg2+ and Ca2+ is more obvious at pH values of 9 and 10, respectively, which correlates with the pH values at which the first hydroxy-complexes of these divalent cations start forming. This seems to indicate that depressing effect of kaolinite on chalcopyrite in seawater may be related to formation of hydrolyzed species of calcium and magnesium. These species can induce heterocoagulation between kaolinite and chalcopyrite. The trends observed in the micro-flotation experiments are in good agreement with the results of the induction time measurements and slime coating tests.

12

Froth flotation of Aljustrel sulphide complex ore

Sousa R., Futuro A., Pires C. S., Leite M. M.

Physicochemical Problems of Mineral Processing

|

2017

|

Vol. 53, iss. 2

758--769

EN

Froth flotation of copper-zinc-lead ores is a complex process based on similar metallurgy processing and strong interactions between chalcopyrite and sphalerite. These types of ores represent 15% of the world production and 7.5% of copper deposits all over the world. In the present study, an attempt is made to assess the feasibility of froth flotation of a complex sulphide ore, where the effect of liberation grade as well as depressant, collector and frother dosage was studied. Copper flotation is dependent on the mineral liberation grade, which is significantly related with the size distribution. It was shown that longer grinding time increased the Cu grade but decreased the copper recovery due to the presence of very fine particles. Lime and sodium metabisulphite, used as depressants, allowed to achieve a good flotation performance. It was shown that for this type of ore lower dosage of the collector should be applied. Finally, a higher frother dosage led to a greater selectivity and reduced entrainment of very fine particles, but also caused low kinetic ratio and low recovery of valuable minerals. A well-defined flotation objective was imperative for a good liberation grade and reagents dosage selection, mainly for complex sulphide ores. A useful contribute was given to a better technical understanding of flotation of a complex sulphide ore from the Moinho deposit.

13

A study of the effect of operating parameters in column flotation using experimental design

Bedekovic G.

Physicochemical Problems of Mineral Processing

|

2016

|

Vol. 52, iss. 2

523--535

EN

The effect of air flow rate, pulp density and particle size was studied using central composite design for coal samples from the Lazy mine. Evaluation of column flotation tests was based on two dependant variables such as ash content and combustible matter recovery in the concentrate. The ash content in the concentrate was from 4.61 to 9.62% with the recovery of combustible matter from 17.43 to 81.98%. The ANOVA statistical analysis showed that the main effect of air flow rate has a significant impact on the combustible matter recovery and ash content in the concentrate. The main effect of pulp density on the combustible matter recovery is significant, whereas for the ash content it is not seen. There is a strong effect of the particle size on the ash content and combustible matter recovery in the concentrate. The interaction of the effect of the pulp density and particle size has a significant impact on the ash content in the concentrate.

14

Ewolucja odczynników flotacyjnych do flotacji węgla kamiennego

Tora B., Kurzac M.

Przegląd Górniczy

|

2011

|

T. 67, nr 7-8

99--103

PL

W artykule przedstawiono podział odczynników flotacyjnych stosowanych do flotacji węgla kamiennego w zależności od ich składu chemicznego i sposobu produkcji. Przedstawiono najbardziej nowoczesne odczynniki stosowane do flotacji węgla w polskich zakładach wzbogacania – odczynniki RF oraz odczynniki Bio.

EN

The article presents the division of flotation reagents used for hard coal flotation according to their chemical composition and production method. The most modern reagents used for coal flotation in Polish preparation plants were presented – the RF reagents and Bio reagents.

15

Wpływ rodzaju odczynników na skład fazowy piany w procesie flotacji węgla

Małysa E., Hanc A.

Przegląd Górniczy

|

2010

|

T. 66, nr 3-4

103-106

PL

Właściwości piany powstającej w maszynce flotacyjnej są jednym z istotnych czynników wpływających na proces flotacji węgla. W pracy przedstawiono wyniki badań wpływu ilości i rodzaju odczynników na nawodnienie produktów pianowych we flotacji węgla surowego z kopalni "Jankowice". Wykazano, że ilość wody wynoszonej do produktu pianowego zależy od ilości odczynnika oraz od czasu trwania procesu. Ilość wody zebrana w koncentratach rośnie wraz ze stężeniem odczynnika i czasu flotacji. Stwierdzono korelację pomiędzy wychodami koncentratów oraz uzyskami części lotnych i palnych a ilością wody w produkcie pianowym dla odczynników flotanolu, centrifroth, RF-B oraz 1-heksanolu. Natomiast w przypadku montanolu i oktanolu ilości wody w koncentratach rosną ze wzrostem ich stężenia, pomimo, że wychody tylko nieznacznie zmieniają się.

EN

Properties of forth formed in flotation machine are one of essential factors influencing coal flotation process. Results of quantity and kind of flotation agents influence on water content in froth products at flotation of raw coal fines in the mine "Jankowice" are presented. It has been proved that quantity of water brought into the froth product depends on agent quantity and process duration time. Quantity of water collected in concentrates grows along with agent concentration and time of flotation. Correlation has been stated between concentrate yields as well as outputs of volatiles and combustible matter and quantity of water in the froth product for agents: flotanol, centrifroth, RF-Band and 1-hexanol. However in case of montanol and oktanol of water grows along with their concentration, in spite of only slight changes yields.

16

Nowe kierunki badań oraz rozwoju odczynników do flotacji węgla oraz minerałów niepolarnych

Vidlar J., Pasiowiec P.

Inżynieria Mineralna

|

2009

|

R. 10, nr 2

1-7

PL

Podczas wydobycia oraz przeróbki mechanicznej węgla kamiennego oraz szeregu materiałów naturalnie hydrofobowych (grafit, siarka samorodna, talk, molibden, mika) powstaje i jest podawana przeróbce mechanicznej duża ilość drobnych ziaren surowca użytecznego (tzw. mułów), które występują w postaci zagęszczonych zawiesin wodnych lub zawiesin rozcieńczonych, traktowanych jako zanieczyszczone wody ściekowe. Najbardziej skuteczną metodą pozyskiwania użytecznych składników mineralnych z takich zawiesin wodnych (tzw. mułów flotacyjnych) jest flotacja pianowa. W ostatnich latach flotacja wykorzystywana jest coraz częściej jako metoda oczyszczania ścieków przemysłowych, zanieczyszczonych substancjami nieorganicznymi i organicznymi oraz jako metoda zagęszczania trudno sedymentujących mułów. W laboratoriach badawczych Wydziału Górnictwa i Geologii Vysokiej Skoly Banskiej w Ostrawie (HGF VŠB-TUO) przeprowadzono badania rozwojowe, których celem było uzyskanie pełnowartościowych odczynników flotacyjnych zastępując składniki ropopochodne składnikami pochodzenia biologicznego. Nowym perspektywicznym kierunkiem w zakresie opracowywania receptury odczynników flotacyjnych do flotacji mułów węglowych (uwzględniając skokowy rozwój branży produkcji biopaliw silnikowych-MEŘO) okazały się być badania oraz wdrożenia odczynników flotacyjnych na bazie komponentów odpadowych i produktów pośrednich tych biotechnologii. Skład nowo wytwarzanych odczynników flotacyjnych opiera się na doborze dostępnych składników pochodzenia biologicznego, mianowicie składników hydrofobowych i składników spieniających. Próby przemysłowe potwierdziły żądaną skuteczność technologiczną a zwłaszcza efektywność ekonomiczną zastąpienia stosowanych do tej pory odczynników flotacyjnych petrochemicznych nowo wytworzonymi odczynnikami bio.

EN

During mining and mechanical processing of hard coal and some naturally hydrophobic materials (graphite, nugget sulphur, talcum, molybdenum, mica), a great quantity of small molecules of sludge of the extracted usable raw material is created and mechanically processed afterwards. The sludge appear as concentrated water slurry or diluted suspensions defined as polluted drain waters. The most efficient method to separate usable mineral components from water slurry (so-called "flotation sludge") is froth flotation. Recently the flotation is still more often used as a method of treatment of industrial waste, polluted with organic and non - organic substances, and as a concentration method for sludge of difficult sedimentation. In the research laboratories HGF VSB-TUO development researches has been done in order to find components of biological origin that are of full value and can replace currently used petrochemical components of flotation reagents. The research and implementations of flotation reagents based on waste components and indirect products of these technologies proved to be a new perspective direction in the area of defining flotation reagents for the flotation of coal sludge (taking into consideration an accelerated development of the branch of engine bio fuels production - MERO). The composition of new flotation reagents is based on the preferences of available components of biological origin, i.e. hydrophobic and frothing ones. The exploitation tests proved the required technological efficiency and, in particular, the economic benefit obtained by substituting the petrochemical flotation reagents used until now with new created reagents.